The invention relates to a device for testing the operation of an antiskid control system.
As is known, the braking of a motor vehicle equipped with an antiskid control system may lead to very dangerous situations in the event of a defect occurring in the electronic installation of the antiskid control system. It is therefore necessary to provide safety circuits which, when defects occur, detect them and, by means of error or switch-off signals, prevent dangerous and inadmissible antiskid control action. Consequently, it is necessary to check, from time to time or preferably, at certain time intervals during various operating conditions of the vehicle, the electronic switching devices which serve the purpose of controlling fluid pressure modulator valves, for operability and operating reliability.
A known checking device of the type mentioned functions by generating a simulated control signal by short-circuiting the speed indicator or sensor, followed by checking as to whether the system responds to a signal so produced. It is a disadvantage that when short-circuiting the sensor it is no longer possible to know at which moment the short-circuiting may be discontinued again, thus creating the danger that undetermined cycle-duration remnants are measured and utilized, and thus, briefly, speed values are found which are too high.
Furthermore, a checking device is known which enables checking as to the proper functioning of the antiskid control system only before starting to drive the vehicle, i.e. when it is standing still.